1. Field of the Invention
The present invention relates to a solid state image pickup apparatus (solid state image pickup element), such as a CCD sensor and a CMOS sensor, and a method for manufacturing the same.
2. Description of the Related Art
For the solid state image pickup apparatus, a technique for increasing the light collecting efficiency to light receiving portions, particularly a technique for more efficiently collecting light with sharp incident angle, has been expected. For example, Japanese Patent Laid-Open No. 2006-295125 has proposed a solid state image pickup apparatus having a structure in which hollow portions are formed in regions equivalent to the circumference of light receiving portions to thereby increase the light collecting efficiency to the light receiving portions utilizing the reflection on the interface of the hollow portions.
Specifically, Japanese Patent Laid-Open No. 2006-295125 discloses a technique for forming the above-described hollow portion between each color filter provided above each light receiving portion in such a manner as to correspond to each light receiving portion.
More specifically, according to Japanese Patent Laid-Open No. 2006-295125, for the formation of the above-described hollow portion, first, a photosensitive resin layer is formed on a color filter formation film, and then the photosensitive resin layer is selectively exposed to thereby form a photoresist containing the photosensitive resin layer. Then, etching using the photoresist as a mask is performed to form grooves in the color filter formation film to thereby form a plurality of color filters and also form the hollow portion between each color filter.
However, due to the exposure limit of the photoresist (i.e., limitation by the minimum pattern when developing the photoresist), there has been a limit in narrowing the opening width of the photoresist. According to the technique of Japanese Patent Laid-Open No. 2006-295125 described above, there has been a limit also in narrowing the width of the hollow portion formed between each color filter. For example, according to the technique of Japanese Patent Laid-Open No. 2006-295125 described above, it is difficult to form a hollow portion with a width of about 0.1 μm. Thus, when it is difficult to narrow the width of the hollow portion formed between each color filter, the area occupied by the color filter per pixel becomes small, so that a concern about a reduction in light detection sensitivity by the light receiving portions arises.